The present invention relates to cutoff saws. In particular, the invention involves an improved device and method for clearing away cutoff debris in the cutting vicinity of a cutoff saw, thereby minimizing machine jamming and allowing faster throughput. The invention allows cutoff debris to be cleared immediately after cutting, even prior to the blade returning to its non-cutting position, thus preventing the debris from falling into the saw blade slot. The invention is useful, for example, in a cutoff saw such as the one disclosed and claimed in co-pending U.S. patent application Ser. No. 07/792,610, now U.S. Pat. No. 5,181,445, which is hereby incorporated by reference.
The yield obtainable for a given cutoff saw directly depends on how fast the saw is capable of running. One significant limitation on a saw's running speed is its ability to clear cutoff debris from the conveyance path. Cutoff debris typically includes wood pieces varying in size from small wood dust particles to relatively large excised board sections. As the saw's running speed is increased, the tendency for cutoff debris to jam the machine increases. When jamming occurs, the machine must be stopped, thus negating the goal of increasing yield, i.e., board throughput.
Another problem caused by wood debris in the conveyance path is that it can adversely affect cutting accuracy. Wood debris which remains on the conveyor or which becomes lodged in the vicinity of the saw blade may displace the object board causing deviations from the desired cutting line.
Prior attempts to solve the problems discussed above have proven unsatisfactory. For example, prior cutoff saws have included mechanisms for clearing cutoff debris from the downstream conveyor. This approach is flawed because by the time the debris reaches the downstream conveyor it is often too late to avoid jamming. Others have tried to employ a vacuum mechanism for removing cutoff debris downstream from the saw blade. This approach is also quite limited because, although it may be capable of removing fine particles such as wood dust, it is not satisfactory for removing larger cutoff debris such as knots or excised board sections which are the primary causes of machine jamming.